diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index da19a75bd..29737154f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1227,6 +1227,7 @@ set( GAME_SOURCES
 	common/filesystem/source/fs_findfile.cpp
 	common/filesystem/source/fs_stringpool.cpp
 	common/filesystem/source/unicode.cpp
+	common/filesystem/source/critsec.cpp
 
 )
 
diff --git a/src/common/filesystem/source/resourcefile.cpp b/src/common/filesystem/source/resourcefile.cpp
index 81d307000..b592d2bfa 100644
--- a/src/common/filesystem/source/resourcefile.cpp
+++ b/src/common/filesystem/source/resourcefile.cpp
@@ -709,7 +709,7 @@ FileReader FUncompressedFile::GetEntryReader(uint32_t entry, bool newreader)
 	FileReader fr;
 	if (entry < NumLumps)
 	{
-		if (!Entries[entry].Flags & RESFF_COMPRESSED)
+		if (!(Entries[entry].Flags & RESFF_COMPRESSED))
 		{
 			if (!newreader)
 			{